Portable Dispensing Devices
Medical treatment of some illnesses requires continuous (or periodic) drug infusion into various body compartments through, for example, subcutaneous and intra-venous injections. Diabetes mellitus patients, for example, require administration of varying amounts of insulin throughout the day to control the blood glucose levels. In recent years, ambulatory portable insulin infusion pumps have emerged as superior alternatives to multiple daily syringe injections of insulin. These pumps, which deliver insulin at a continuous, or periodic, basal rate as well as in bolus volumes, were developed to liberate patients from repeated self-administered injections, and to allow them to maintain a near-normal daily routine. Both basal and bolus volumes generally have to be delivered in precise doses, according to an individual prescription, since an overdose or under-dose of insulin could be fatal.
The first generation of portable insulin pump included “pager-like” devices attached to patients' belts. A first generation device included a reservoir within the device housing. A long tube delivered insulin from the pump attached to a patient's belt to a remote insertion site. Examples of such first generation devices are described, for example, in U.S. Pat. Nos. 3,631,847, 3,771,694, 4,657,486 and 4,544,369, the contents of all of which are hereby incorporated by reference in their entireties. These first generation devices included a control panel combined with the pump, resulting in a device with relatively large dimensions. Although bulky, large, and heavy, these first generation devices were an improvement over multiple daily injections. Nevertheless, the first generation devices were uncomfortable, bulky devices with long tubes. Consequently, these first generation devices were rejected by the majority of diabetic insulin users because the devices impacted regular activities, such as sports (e.g., swimming).
To avoid the noted consequences of using a long delivery tube of the infusion set, a new concept, referred to as a second generation pump, was proposed. This concept included a remote controlled skin securable (e.g., adherable) device with a housing having a bottom surface adapted to be secured to the patient's skin, a reservoir disposed within the housing, and an injection needle in fluid communication with the reservoir. These skin securable devices were generally discarded every 2-3 days, in a manner similar to that existing with other commercial pump infusion sets. Second generation devices are disclosed, for example, in U.S. Pat. No. 5,957,895 to Sage, U.S. Pat. No. 6,589,229 to Connelly and U.S. Pat. No. 6,740,059 to Flaherty, the contents of all of which are hereby incorporated by reference in their entireties. Additional configurations of skin securable pumps are disclosed, for example, in U.S. Pat. No. 6,723,072 to Flaherty and U.S. Pat. No. 6,485,461 to Mason, the contents of all of which are hereby incorporated by reference in their entireties.
The second generation skin securable infusion devices are typically heavy and bulky and generally cause discomfort when carried by the user. Additionally, these devices are relatively expensive. The entire device, including the relatively expensive components (e.g., electronic modules, a driving mechanism, etc.) is generally discarded every 3 days or so. Furthermore, although there are situations in which patients would like to temporarily disconnect the pump (e.g., when taking hot showers, entering a sauna, etc.), these second-generation devices cannot be reconnected after being disconnected.
Third generation devices provides a more cost-effective solution and allow more diverse use of an infusion device. An improvement to this third generation skin securable pumps includes the use of two parts, as described, for example, in co-pending/co-owned U.S. patent application Ser. No. 12/004,837 and International Patent Application No. PCT/IL07/001578, the contents of which are hereby incorporated by reference in their entireties. These applications disclose embodiments directed to systems, devices and methods for connecting and disconnecting a skin securable dispensing unit/device. Such embodiments sometimes utilize a cradle unit which is initially adhered to the skin and then has a cannula inserted through the cradle unit into the body of the user. Insertion can be performed automatically by a dedicated inserter device, or may be performed manually. The dispensing unit of the device can also be connected and disconnected to and from the skin-adhered cradle at the patient's discretion. This implementation enables versatile operational modes, including manual and automatic cannula insertion modes, use of cannulae with various lengths and insertion of a cannula at various insertion angles. The cradle is disposable and relatively inexpensive and may be discarded every 2-3 days. Unlike second generation infusion pumps, in situations involving site misplacement of the cannula (resulting in scarred tissue, bleeding, cannula kinking etc.), only the cradle and cannula may have to be disposed and replaced, rather than the whole (and relatively expensive) device which includes the reservoir still containing unused insulin.
Ambulatory portable drug delivery devices and some medical sensors require a relatively large volume of information relating to parameters and conditions of the treatment, the device and medical/health state of the patient. Such information and data typically include characteristics of the drug dosage, data relating to the conditions of the patient's body and data associated with the device operation. The data is typically transferred between a remote control, dispensing device and sensors for measuring bodily level analyte (e.g., glucose), via, for example, wireless RF communication.
Dispensing Device and Remote Control Communication
Transmitting the data between a dispensing device and a remote control (also referred to as a remote control unit and/or remote controller, together with the dispensing device may also be referred to as a dispensing system; each also may be individually referred to as a unit, where a device may comprise one or more units) give rise to certain problems. First, the transmission between a remote control and a dispensing device may be corrupted or disrupted, e.g., the signal may be corrupted due to low signal to noise ratio (SNR). Another drawback is that there are only a limited number of frequencies open for transmissions, e.g., the frequencies in the Industrial, Scientific, and Medical (ISM) radio band. However, the ISM radio band may be supporting many other wireless devices, such as wireless devices equipped with WiFi, Bluetooth, wireless USB and the like. These wireless transmission techniques and protocols are used by many devices, such as cordless telephones, cellular phones and their accessories, personal computers, hand held computers, and the like. Furthermore, there are additional devices, such as microwave ovens, switches, and electric motors that cause radio frequency interference (RFI) in the ISM radio band. As wireless and miniaturization technologies improve, electrical devices' reliance on wireless as a mechanism for communications will continue to rise, thus exacerbating interference problems (e.g., causing jamming and noise problems). The multiplicity of communications and messages sharing similar (or the same) frequencies may also give rise to problems related to receiving false messages, jamming, low signal to noise ratio, high radio frequency interference and the like.
Communications problems and programming of infusion pumps may be particularly critical with respect to implantable devices. Implantable infusion pumps for infusion of, e.g., insulin, are described, for example, in U.S. Pat. Nos. 4,494,950 and 5,558,640 and in the publication by W. Schubert et al., “An implantable artificial pancreas,” Medical and Biological Engineering & Computing, 1980, 18, pp. 527-537, the contents of all of which are hereby incorporated by reference in their entireties. In the latter document, an artificial implantable pancreas is described in which in a first mode of operation, a glucose sensor transmits the actual blood glucose level to a control unit, and the amount of insulin to be infused may then be calculated on the basis of patient specific parameters recorded in a program memory. Corresponding control signals for a dosing unit to be infused may subsequently be determined by performing a control procedure. If no sensor is used or if the sensor employed fails, the dosing unit is controlled in accordance with a second mode of operation by a stored dosing program. Thus, the first mode of operation corresponds to a closed control loop and the second mode of operation corresponds to an open control loop.
Safe operation of a remotely controlled delivery device typically depends, at least in part, on control commands sent from a remote control unit. The commands should be received only by the specific delivery device that is to be controlled. Other delivery devices in the vicinity of the user that also happen to receive the transmitted command should not perform operations in response to such received commands. Further, as the delivery device may be adapted to transmit data to the remote control, such information should generally be received and acted upon only by the corresponding control unit. Such an implementation issue has to be considered with respect to both second and third generation dispensing devices. To provide proper security, any two units intended to work together will normally be “paired” by exchange of information between the two units, enabling robust data communication between the two units (e.g., employing some recognition and/or encoding procedure unique to that particular pair of devices).
A medical system that includes a safe pairing mechanism is described, for example, in International Patent Publication No. WO 2007/104755, the content of which is hereby incorporated by reference in its entirety. In that system, a medical system is provided comprising a first unit and a second unit. Both of the units includes two communication mechanisms, the first having a short range (e.g., Near Field Communication) for transmitting and receiving some of the communications, particularly pairing commands and commands related to bolus delivery, and a second communication mechanism having a longer range (and thus less secured) for communicating other massages. Including two communication mechanisms in the same unit may result in bigger and bulkier housing and in higher costs.